SU1265923A2 - Device for measuring instantaneous values of currents in commutated sections of electric machines - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to increase the reliability and expand the field of research of switching quality. The device includes a series of electrically insulated parts 1-3 along the length w, the wires installed before contact with the collector, the lamellae 4-10 of which are connected to sections 11 -16 of the winding of the core. The device is equipped with an external synchronization unit and a control unit that contains two circuits. The first circuit includes a DC amplifier on the photodiode, a reed switch. The second control circuit includes a power supply,. to the output ends of which are connected three parallel branches. The external synchronization unit contains a light source connected to a power source. A synchronized slotted disc is mounted on the machine shaft. When shorting the resistance in the core chain, a transitional mode occurs. The device makes it possible to measure instantaneous currents in all sections of the core of the test machine. The device allows you to determine the true values (for currents, which makes it possible to make adjustments to the development of devices to improve switching. 3 Il.

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The invention relates to a measurement technique, in particular, to measurements during testing of electric machines, in particular, devices for measuring current in switched sections in transient conditions, and is an improvement of the device according to the author. St. No. 782055.

The aim of the invention is to increase the reliability and expand the field of research into the quality of switching of an electric machine.

FIG. 1 shows a device for measuring instantaneous currents in switched sections in transient conditions; in fig. 2 is a diagram of a control unit and a synchronization unit; in fig. 3 - principle scheme of imitation of transient modes.

A device for measuring instantaneous values of the current of the switched section in transient modes includes a series of electrically isolated parts 1–3 along the length of the grid (Fig. 1). Parts 1-3 of the brush are mechanically connected (directly or with the help of brush holders) to the finger of the brush holder (not shown) and installed before contact with the collector, the lamellae 4-10 of which are connected to sections 11 -16 of the winding box. To simplify, the number of brush floors in this example is assumed to be 2. Therefore, the number of parts 1-3 of the brush is one more, i.e., equal to 3. Parts 1-3 of the brush are electrically connected to the clip 17 of the external circuit through individual measuring resistors 18-20, measuring leads 21-23 of which are connected in pairs to the inputs of subtractive devices 24-26, the outputs of which are connected to the input terminals 27 of a multichannel current meter 28 (multipath oscilloscope). The working surface of the collector is partially insulated by brush tracks in a staggered order at intervals; uninsulated plate section - a group of isolated plate sections, the number of which is not less than brush floors. Isolated areas of the plates are formed, for example, by electrically insulating overlapping (enamels, varnishes, films), the thickness of which and the coefficient of friction of brushes for which practically do not change the behavior (mechanics) of the sliding contact. The thickness of the intervals of 29 1 -1.5 mm. The core of the tested machine rotates counterclockwise 30. The insulated plate sections (hatched) can be formed by deepening the corresponding plate sections and labeling these areas of insulated plates from the plate, including from the same material as the plates, for example from collector copper. After reworking, the working surface of the collector is polished to give it a strictly cylindrical shape. In this case, the surface of the insulated and uninsulated areas of the plates along the brush tracks consists of one material, which improves the dynamics of the sliding contact.

The control unit 31 (Fig. 2) in the first circuit includes a DC amplifier that contains a series of resistors 32, photodiode 33, and a base-emitter junction of the transistor 34 connected to the amplifier's power supply 35. The output ends of power supply 35 are connected in series with a chain of coil 36 and reed switch contact 37, the common point of which is connected to the collector of transistor 34. In the second circuit, unit 31 contains a power supply 38, to the output ends of which are connected three parallel branches, one of which from the series 39 contacts of the reed switch relays 39 and the time relay coil 40, the second one from the contact block 41 and the time relay coil 42 and the last branch from the contact block 43 and the control coil 44 of the power contactor 45 (Fig. 3). The external synchronization unit 46 comprises light sources 47 and 48, the outputs of which are connected via a push-button switch 49 without self-return to the power supply 50, and a synchronization disk 51 with slots 52 and 53 for mounting it on the shaft of an electric machine. The light sources 47 and 48 through the slots 52 and 53 of the synchronization disk 51 direct the light beams to the photodiodes 33 and 54. The first circuit includes a DC amplifier, which contains a series circuit of a resistor 55, a photodiode 54, a base-emitter junction of the transistor 56, connected one end to the minus of the power supply source 57 of the amplifier, and the other through the auxiliary contacts 58 to the plus source of the power supply 57. One end of the coil 59 of the reed switch is connected to the minus of the power supply 57, and the other to the collector of transistor 56, the auxiliary contact 58 of the time relay is connected to the plus of the power supply 57 and the other to the emitter of the transistor 56. The second circuit consists of series-connected power supply 60 and contact 61 of a reed switch connected to synchronization input 62 of current meter 28.

The device works as follows.

Claims (1)

When the electric machine operates in continuous mode according to the scheme of direct load (Fig. 3), switching on the switch 49 supplies the sources 47 and 48 of the light from the power source 50. When a beam from the source 47 of light passes through the slit 52 to the photodiode 33, the transistor 34 opens and the coil 36 of the reed switch operates, closes contacts 37 and 39. When the contact 37 is closed, a constant power is supplied to the reed switch coil 36 from the power source 35. When contact 39 closes from source 38, power is supplied to time relay coil 40. At the same time, normally open block contacts 41 and 43 are closed, and power supply 38 is energized by time relay coil 42 and control contactor coil 44 of power contactor 45, which short-circuits resistance 63 in the main circuit of the test machine (Fig. 3), which leads to a transition mode i.e., a jerky change in the core current in the power circuit. When power is applied to the coil 42, the auxiliary contact 58 is closed in the initial period of the transition mode. At this moment, through the slot 53 of the rotating synchronizing disk 51 from the light source 48, the beam hits the photodiode 54 and opens the transistor 56, which ensures the coil 59 of the reed switch and the contact 61 to close. A voltage pulse from the power source 60 is applied to the input 62 synchronization meter 28 current (electronic oscilloscope). The supply of a voltage pulse triggers a single-start sweep of the current meter 28. Since the start of the sweep, the signals from the resistors 18-20 are fed to the inputs of the subtracting devices 24-26, and from their outputs to the current meter 28. Thus, by using an oscillographic pairwise difference in voltage across measuring resistors, it is possible to measure the instantaneous values of currents in all sections of the test machine's core in transient conditions. The technical and economic effect from the use of the proposed device consists in increasing the switching reliability and expanding the field of studying the quality of switching electrical machines. Switching reliability is ensured by the correct choice of current loads in transients, not causing burning of the bars and collector plates, and setting the current protection of the electrical machine, preventing the formation of circular lights on the collector. Expanding the field of research of switching quality consists in determining the true instantaneous values of currents in switched sections in transient modes, which allow to establish the nature of their changes depending on the configuration of parameters of the switching node and on the operating modes of the electrical machine, to make adjustments to the calculation methods, to develop various devices to improve switching and identify ways to improve the quality of switching. Claims An apparatus for measuring instantaneous current values in switched sections of an electrical machine according to the author. St. No. 782055, characterized in that, in order to increase the reliability and expand the area of electrical commutation quality testing, it is equipped with an external synchronization unit and a control unit that contains two circuits, the first control circuit includes a DC amplifier on the photodiode, a reed switch. in which a series of coils and one contact is connected to the output ends of the amplifier power supply, and the common point of the coil and the contact of the reed switch is connected to the collector of the amplifier transistor, the second the control circuit includes a power source, to the output ends of which three parallel branches are connected, one of which consists of a series-connected reed switch and a time relay coil, the second is from the contact block and a time relay coil, and the last is from the time relay contact and coil control of the power contactor, the external synchronization unit contains a light source with leads for connecting to a power source, a synchronization disk with slots, designed to be mounted on an electric machine shaft There are two circuits, the first synchronization circuit includes a DC amplifier on the photodiode, a reed switch, the coil of which is connected at one end to the power supply minus of the amplifier, and the other to the collector of the amplifier transistor, the contact block of the relay is connected at one end to the positive source the power of the amplifier, and the other to the emitter of the transistor of the amplifier, the second synchronization circuit consists of a power supply, a reed switch connected to the current meter input, sequentially connected to a power source.